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Published January 29, 2014 | Published + Supplemental Material
Journal Article Open

Ultrasonically encoded wavefront shaping for focusing into random media


Phase distortions due to scattering in random media restrict optical focusing beyond one transport mean free path. However, scattering can be compensated for by applying a correction to the illumination wavefront using spatial light modulators. One method of obtaining the wavefront correction is by iterative determination using an optimization algorithm. In the past, obtaining a feedback signal required either direct optical access to the target region, or invasive embedding of molecular probes within the random media. Here, we propose using ultrasonically encoded light as feedback to guide the optimization dynamically and non-invasively. In our proof-of-principle demonstration, diffuse light was refocused to the ultrasound focal zone, with a focus-to-background ratio of more than one order of magnitude after 600 iterations. With further improvements, especially in optimization speed, the proposed method should find broad applications in deep tissue optical imaging and therapy.

Additional Information

© 2014 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ Received: 05 November 2013; Accepted: 10 January 2014; Published online: 29 January 2014. This work was sponsored in part by the National Academies Keck Futures Initiative grant IS 13 and National Institute of Health grant DP1 EB016986 (NIH Director's Pioneer Award). Author contributions: J.W.T. and P.L. designed and ran the experiment. J.W.T. wrote code for the experiment and simulations. P.L. implemented the PR detection system. J.W.T., P.L. and Y.S. prepared the manuscript. L.V.W. provided overall supervision. All authors were involved in analysis of the results and manuscript revision. Competing financial interests: J.W.T., P. L. and Y.S. declare no competing financial interests. L.V.W. has financial interests in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.

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Supplemental Material - srep03918-s1.pdf

Supplemental Material - srep03918-s2.avi


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